Distribution and symmetrical patellofemoral pain patterns as revealed by high-resolution 3D body mapping: a cross-sectional study

Abstract

BackgroundDetailed pain mapping of extent and distribution in individuals with patellofemoral pain (PFP) within and around a complex structure such as the knee has yet to be explored.MethodsPerceptions of on-going pain from adolescents and young adults (N = 35) with long-standing (>10 months) PFP were collected on high-resolution 3D digital body-schema of the knees. Location, area of pain, pain intensity, laterality, worse side of knee pain, symptom duration, and symmetry in bilateral knee pain were recorded. A threshold for naturally occurring variations in symmetrical knee pain drawings were collected from 18 healthy controls and used in combination with the development a symmetry index (0–1) to create a fuzzy rule for classifying symmetrical and non-symmetrical PFP patterns as compared to a PFP expert. The symmetry index was computed and tested using a correlation coefficient alone or in combination with the Jaccard index and the true and false positive rates (TPR and FPR, respectively) determined.ResultsThe peripatellar region was the common report of pain location however, novel and nonconforming PFP patterns were identified and the majority of individuals (22 of 27) with bilateral PFP expressed highly-symmetric mirror-image pain. Individuals with symptom duration of 5 years or more had a greater area of pain, compared to those with symptoms for less than 5 years. The total area of pain was correlated to symptom duration for those with extended symptoms durations and a progression towards an “O” shaped pattern emerged. A TPR of 100% for identifying symmetrical knee pain patterns was found however the expert PFP tended to be stricter, as reflected in FPR of 20%.ConclusionsA high proportion of PFP patterns or symptoms occur in mirrored locations and are exceptionally symmetrical, and long duration of symptoms appear to converge to an ‘O’ shape. Classifying symmetrical pain patterns is subjective however simple fuzzy rules and correlations can be used to increase objectivity. This study highlights a gap in knowledge of PFP symptom presentation, reveals what may be a natural progression of symptoms, and provides valuable clinical insight for both pain management and treatment.Electronic supplementary materialThe online version of this article (doi:10.1186/s12891-017-1521-5) contains supplementary material, which is available to authorized users.

The psychological features of patellofemoral pain: a cross-sectional study

“…Patellofemoral pain (PFP) is a common and frequently persistent condition that presents as pain behind or around the patella [1,2]. It is typically considered to have a mechanical aetiology, aggravated when the knee is loaded in a flexed position [3], with ensuing functional limitations in daily physical tasks and sporting activities [4].…”

Digital body maps reinvent the way we perceive and discuss pain and discomfort

“…Moreover, the amount of detail, as shown in Figure 2, and easier quantification of pain areas and patterns are more readably achieved with digital solutions. Additional benefits include the ability to contrast one or more pain drawings at different time points, to determine common features within or between patient populations [4,5], and to map other qualities of pain or discomforts [11], such as burning or aching sensations. indeed, other methods of digitizing pain drawings exist, such as scanning paper drawings and modifying pre-existing paint and drawing tools [4].…”

“…in the recent two decades, data stemming from simple methods of musculoskeletal pain drawing have helped to reveal the significance of single versus multi-site pain reports. Presently, digital pain mapping studies show that there may be hidden patterns of pain expression within these marked pain sites [5].…”

“…The revival of pain drawings as digital body maps for visualizing pain [1][2][3][4][5] and discomfort changes the way we understand patients and communicate with them [1]. A review of the literature following the introduction of pain drawings suggests that little information about a patient's condition can be extracted from the pain drawing alone.…”

Peer Review #1 of "Capturing patient-reported area of knee pain: a concurrent validity study using digital technology in patients with patellofemoral pain (v0.2)"

“…Recent studies have investigated pain drawings recorded on digital platforms and shown reliability commensurate with that of paper drawings [11 12] A study using high-resolution and contoured (3D) images of the knee found a high proportion of patients with patellofemoral pain (PFP) reported knee pain in mirrored locations and that the pain drawings were exceptionally symmetrical. [12] Interestingly, when the knee pain drawings were compared to duration of symptoms, those with a longer duration of symptoms appeared to draw patterns more of an 'O' shape. Given that longer duration of PFP symptoms has been shown to be a prognostic indicator of a poor outcome, [13] capturing pain areas digitally will allow quantification and real time insight into the patient's condition, which may optimise patient management.…”